This invention relates to a process for determining tumor-associated glycolinkage (hereinafter abbreviated as TAG) in body fluid of a mammal, i.e., TAG including glycoproteins, glycopeptides, glycolipids and/or sugars containing galactose-(.beta.1.fwdarw.3 or .beta.1.fwdarw.4)-N- acetylglucosamine or galactose-(.beta.1.fwdarw.3 or .beta.1.fwdarw.4)-N-acetyl- galactosamine terminus which increases with the proliferation of undifferentiated cells, particularly tumorous cells or cancerous cells, and to a method for diagnosing of cancer by determining the above-described TAG.
As a method for diagnosing cancer, it has been conducted to measure a specific glycoprotein which is specifically yielded in patients suffering cancers. This method mainly utilizes the antigenicity of protein moiety of the glycoprotein; for example, there are known diagnosis of primary cancerof the liver by measuring .alpha..sub.1 -fetoprotein and diagnosis of cancer of a digestive organ, particularly cancer of the rectum, by measuring CEA ["Igaku no Ayumi (Progress in Medicine)", Vol. 106, No. 5, Fifth Saturday Special Issue, pp. 235-250 (1978)]. However, these diagnostic methods are comparatively limited in their applicability, and there has been desired a diagnostic method for diagnosing a wide variety of cancers.
No methods of diagnosing cancers by utilizing the binding specificity of sugar residue of tumor-associated glycolinkage have so far been known.
It has been found that body fluid of a patient with cancer contains TAG yielded by undifferentiated cells (mainly cancerous cells) and released into the fluid, and that TAG is considerably different in sugar chain structure, sugar chain length, and kind of constituent sugar residue and, as a result of extensive investigations, it has been found that this TAG includes glycoproteins, glycopeptides, glycolipids and/or sugars having galactose-(.beta.1.fwdarw.3 or .beta.1.fwdarw.4)-N-acetylglucosamine terminus or galactose-(.beta.1.fwdarw.3 or .beta.1.fwdarw.4)-N-acetylgalactosmine terminus, that this TAG specifically combines with lectin, and that presence or absence of cancerous cells, degree of proliferation, prosperity and decay of the cells, and the like can be known by reacting body fluid TAG with lectin, through which cancer can be diagnosed. The present invention has been achieved based on the above finding.